| Bispora sp. MEY-1 is an acidophilic fungal strain isolated from the acidic wastewater of Uranium Mine in Jiangxi, China. Strain MEY-1 shows optimal growth at pH 2.5–3.0 and can secrete several important industrial enzymes, such asβ-glucanase, xylanase, pectinase,β-mannanase, amylase, CMCase,α-galactosidase,β-galactosidase,β-glucosidase and so on.Based on sequence analysis, three glycoside hydrolase genes encoding an endo-β-1,3-1,4-glucanase (bgl7A), a xylanase (xylD) and an endo-polygalacturonase (pga1), were cloned from strain MEY-1 and expressed in Pichia pastoris GS115. The deduced protein sequences showed 50–68% identities to the known proteins, suggesting their novelty. All the proteins were subjected to tertiary structure prediction and catalytic sites were identified, respectively.bgl7A showed the highest amino acid sequence identity of 59.5% to a putative family 7 endoglucanase EG-1 from Aspergillus terreus. Purified BGL7A had three activity peaks at pH 1.5, 3.5, and 5.0 (maximum), respectively, and a temperature optimum at 60°C. The enzyme showed good pH stability at pH 1.0–8.0 and thermostability at 60°C. The Km and Vmax values for barleyβ-glucan were 9.16 mg/ml and 6,737μmol/min/mg, respectively. The specific activities of BGL7A towards barleyβ-glucan and lichenan (4,040 and 2,740 U/mg) were higher than that of carboxymethyl cellulose sodium (CMC-Na; 395 U/mg), which was different from other family 7 endo-β-glucanases.The xylanase gene xylD shared the highest amino acid sequence identity of 49.9% to a putative endo-1,6-β-D-glucanase from Talaromyces stipitatu. Purified recombinant XYLD was more homologous to members of GH 30 based on phylogenetic analysis. The maximal activity of XYLD occurred at pH 3.0 and 60°C. The pH stability and thermostability were good at pH 1.0–6.0 and 60°C, respectively. The specific activity of XYLD towards beechwood xylan, birchwood xylan, 4-O-methyl-D-glucuronoxylan, and oat spelt xylan was 2,463, 2,144, 2,020 and 1,429 U/mg, respectively. The apparent Km and Vmax values for beechwood xylan were 5.6 mg/ml and 3,622μmol/min/mg, respectively.The deduced catalytic domain sequence of PGA1 was 67.2% identical with the polygalacturonase from Colletotrichum Lupini. The optimum pH and temperature were pH 3.5 and 55°C, respectively. The enzyme showed good pH stability at pH 2.0–7.0 and thermostability at 55°C. The specific activity of PGA1 towards polygalacturonic acid and pectin was 1,520 and 725 U/mg. The apparent Km and Vmax values for polygalacturonic acid were 1.25 mg/ml and 2,526μmol/min/mg, respectively. The capacity of PGA1 to reduce the viscosity of apple juice was also determined. The intrinsic viscosity reduction was equal to 7.7% of the initial viscosity value, and the light transmittance was increased more than 84% after treatment with 10 U/ml PGA1.These three enzymes are all acidophilic, having a broad prospects for feed and food industrial applications.
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